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Radioactivity/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby. Tim is holding a frozen package of hot dogs. TIM: These'll take forever to defrost. MOBY: Beep. TIM: Hey, let's just nuke it. Tim places the hot dog package inside a microwave oven. Tim and Moby watch the hot dogs defrost. Moby hands Tim a letter, and Tim reads it. TIM: Dear Tim and Moby, what does it mean when something is radioactive? From, Inez. Well; first of all, microwave ovens aren't radioactive. They shoot microwaves at food, which causes the food particles to move around and give off heat. Radioactivity is the emission of high-energy particles or waves from certain atoms. An animation shows an atom. Wavy lines, smaller clusters of spheres, and small figures that resemble the Sun each shoot out from the core of the atom. TIM: This energy emission happens when the nucleus of the atom partially disintegrates, or falls apart. An animation shows a large cluster of spheres. Wavy lines, smaller clusters of spheres, and small figures that resemble the Sun each shoot out from the cluster. TIM: The process of disintegration is called radioactive decay, and it occurs in atoms that are unstable. MOBY: Beep? TIM: Well, most atoms have stable nuclei. The number of protons and neutrons never changes. An image shows a cluster of spheres. Text reads: protons: 8, neutrons: 8, 16. TIM: But a radioactive atom isn't stable. As it decays, the number of protons, neutrons, and electrons inside the atom changes! The numbers in the text are shown constantly changing. The numbers of protons and neutrons are always different. An animation shows a large cluster of spheres. Wavy lines, smaller clusters of spheres, and small figures that resemble the Sun each shoot out from the cluster. TIM: In other words, it turns into a completely different atom, with different properties! Uranium-238 is a radioactive isotope of uranium. An image shows a cluster of spheres. Text reads: protons: 92; neutrons: 146; 238. MOBY: Beep? TIM: Oh, isotopes are atoms of the same element that have different numbers of neutrons. An image shows a cluster of spheres. This cluster is labeled "oxygen-16". Text reads: protons: 8; neutrons: 8; 16. An image shows a cluster of spheres. This cluster is labeled "oxygen-18". Text reads: protons: 8; neutrons: 10; 18. TIM: Uranium-234 is another isotope of uranium, with four fewer neutrons. Text reads: protons: 92; neutrons: 146; 238. An animation shows a cluster of spheres. Four of the spheres disappear. The numbers 146 and 238 decrease one digit at a time until they reach 142 and 234, respectively. TIM: Anyway, uranium-238 is the most common isotope of uranium, and it’s radioactive. A diagram shows the periodic table of elements. The uranium cell is highlighted. TIM: When its nucleus decays, the uranium-238 turns into a thorium atom. Text reads: protons: 92; neutrons: 146; 238. An animation shows a large cluster of spheres. Wavy lines, smaller clusters of spheres, and small figures that resemble the Sun each shoot out from the cluster. The numbers 92, 146, and 238 change into the numbers 90, 144, and 234, respectively. TIM: The thorium eventually decays into protactinium, which decays into uranium-234, which decays … The numbers 90, 144, and 234 change into the numbers 91, 143, and 234, respectively. The numbers 91, 143, and 234 change into the numbers 92, 142, and 234, respectively. MOBY: Beep! TIM: Well, anyway, long story short, one uranium-238 atom goes through 14 changes before ending up as plain old lead. Text reads: uranium-234. Text reads: protons: 92; neutrons: 142; 234. An animation shows a large cluster of spheres. Wavy lines, smaller clusters of spheres, and small figures that resemble the Sun each shoot out from the cluster. These numbers change fourteen times before ending at 82, 124, and 206, respectively. Text reads: lead-206 TIM: It's impossible to predict exactly when a particular radioactive atom will decay. An animation shows an atom. A wavy line shoots from its core. TIM: But a group of the same radioactive atoms is predictable. Text reads: Uranium-238 An image shows a group of 10 uranium-238 atoms. TIM: If you have a bunch of uranium-238 atoms, you can be sure that half of them will decay into thorium in 4.5 billion years. Text reads: Uranium-238 Text Reads: Thorium-234 An animation shows the group of 10 uranium-238 atoms and a clock. The hands of the clock are spinning. Beside the clock, text reads: 0.5 billion years. A wavy line shoots from five of the atoms one at a time. These atoms change into thorium-234 atoms. The text changes in 0.5 increments until it lands on 4.5 billion years. TIM: The time it takes for half of a group of radioisotopes to decay is that isotope’s half-life. The thorium-234 atoms flash once. MOBY: Beep? TIM: Well, radioactivity can be dangerous, depending on the type of decay that happens. A scientist is analyzing green goo. A circle enlarges from the goo. Inside the circle are four spheres. TIM: Some forms of radioactive decay throw off alpha particles, which aren’t really harmful to us, unless we put them inside our bodies. The green goo begins to glow. The scientist eats the green goo. TIM: Other types of decay throw of beta particles, which can penetrate a few layers of our skin and do some damage. An image shows a group of four spheres. This group is labeled "alpha particle (α)". An image shows a very small figure that resembles the Sun. This figure is labeled "beta particle (ß)". TIM: And some radioactive decay throws off gamma rays, the highest-energy form of electromagnetic radiation. An animation shows a wavy line traveling across the bottom of the screen. This line is labeled "gamma rays (γ)". TIM: Gamma rays can burn our skin, penetrate our bodies' cells, and even mess up our DNA. An animation shows the wavy line travel through a cross section of skin, enter a cell's core, and destroy a double helix of Upper Word DNA. TIM: This can result in cancers and genetic mutations. Human activity creates tons of dangerous radioactive waste every year, and getting rid of the stuff is expensive and difficult. A person dressed in a radioactive suit is carrying a 50-gallon drum of glowing green goo. The drum is labeled with the radioactive symbol. MOBY: Beep? TIM: Well yeah, nuclear radiation has been a big benefit to humans, too. Nuclear power plants, cancer treatments, pacemakers, smoke detectors, and tons of other technologies rely on radioactive decay. The screen is divided into four equal sections. The sections show images of a radioactive plant, a patient undergoing cancer treatment, a pacemaker labeled "ACME heart pacemaker", and a smoke detector. TIM: It's a tough trade-off: radioactivity is incredibly useful, but also incredibly dangerous. The screen is divided into two equal sections. In the first section, an image shows a radioactive plant, a patient undergoing cancer treatment, a pacemaker labeled "ACME heart pacemaker", and a smoke detector. In the second section, an image shows a destroyed double helix of Upper Word DNA. TIM: Oh, and by the way, radioactivity isn't just something humans created; it occurs naturally, too. An animation shows a bird flying over trees and a mountain range. TIM: Just about everything on the planet, from rocks to plants to animals, contains traces of radioactive elements. (microwave oven beeping) TIM: Oh, the hotdogs are defrosted! (sizzling) An image shows Tim and Moby through a microwave oven window. Inside the microwave, the package of hot dogs is melted and smoking. TIM: Oops. I think we left those in too long. Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts